Abstract: A tert-C4–C8-alkyl (meth)acrylate is prepared by reacting (meth)acrylic acid with an olefin of the formula where R1 and R2, which may be identical or different, are methyl or ethyl and R3 is H, methyl or ethyl, in homogeneous phase in the presence of an acidic catalyst and isolating the tert-C4–C8-alkyl (meth)acrylate from the reaction mixture, by a process in which the catalyst is separated off as residue by a two-stage distillation of the reaction mixture and the tert-C4–C8-alkyl (meth)acrylate is isolated from the distillates. The novel process makes it possible to use acetic acid-containing (meth)acrylic acid. The danger of cleavage of the ester and of polymerization of (meth)acrylic compounds is reduced.

Abstract: The present invention relates to a process and a device for evaporating liquids, for example black liquor from cellulose cooking, which contain solid and dissolved substances which are to be concentrated. The liquid is heated to close to boiling temperature in a heat exchanger (1) of the falling-film type. The process is characterized in that the pressure on the liquid side in the falling-film heat exchanger (1) is kept so high that boiling does not take place in this heat exchanger and in that the evaporation takes place, by means of flashing, in a separate expansion tank (7) that has a lower steam.

Abstract: A tert-C4-C8-alkyl (meth)acrylate is prepared by reacting (meth)acrylic acid with an olefin of the formula 1